British Patent No. 2128818B discloses an armature having a commutator in which the commutator segments are connected to the armature winding by mechanical connections. Each commutator segment has a terminal portion provided with a slot which straddles and grips an armature winding portion. The slot is narrower than the winding portion and has an open end for receiving the winding portion and two cutting edges for cutting insulation on the winding portion as the winding portion moves into the slot. The terminal portions are located in respective recesses provided in a rose-like terminal support formed integrally with an electrically insulated commutator segment support.
One of the terminal portions has to make contact with the lead end and the tail end of the winding. The slot in the terminal portion has, therefore, to establish and maintain contact with both ends of the winding and this creates practical difficulties particularly when the winding is of relatively thick gauge wire.
In particular the slots in the terminal portions need to be relatively long in order to receive and accommodate two thick gauge wires especially as it has been found necessary to provide a small recess immediately behind the cutting edges to house the first wire while the second wire is drawn past the cutting edges. This has the result that the axial extent of the terminal portions and the rose-like terminal support is quite large and for a given motor frame size the space available for the commutator is limited so that the axial extent of the brush contacting portions of the commutator segments has to be lessened as compared with a motor having a winding of relatively thin gauge wire.